During detection of sulphur is lassign's test a violet compound with formula `Na_(x)[Fe(CN)_(5)NOS` is formed. What is "x"?

Oxidation number of Fe in violet coloured complex Na_(4)[Fe(CN)_(5)(NOS)] is

Oxidation number of Fe in violet coloured complex Na_(4)[Fe(CN)_(5)(NOS)] is :

The violet colour obtained during the test of sulphur by lassaigne's test is due to the formation of 1) \(Na_{2}[Fe(CN)_{5}S]\) 2) \(Na_{2}[Fe(CN)_{6}\)] 3) \(Na_{2}[Fe(CN)_{5}\)NO 4) \(Na_{4}[Fe(CN)_{5}NOS]\)